A failed attempt to integrate diff-highlight to the core

This is mostly for the record. The patches are not as important as the result in this mail. But if you want to try out, you can.

If you don't know, the script diff-highlight in contrib can highlight changes between two nearly identical lines, pointing out what characters are different. It can improve readability a lot in certain cases (e.g. when you wrap _() around strings).

I approached it differently. I took --color-words and reformatted its output in unified diff format. So you'll see +/- lines like a normal diff, but deleted and added words are also highlighted.

The idea seems to fit well into diff-words machinery. But the output does not, especially in cases where there are many deleted/added words in a chunk. It could look.. patchy, like somebody throwing colors on a wall (especially when you do --highlight-words=.). You can try out and see. git-log works so you can see lots of diff.

I don't know, maybe the idea can be improved to have something closer to diff-highlight. I suppose we can select similar lines and diff them, instead of diff the entire chunk in one go. I might revisit it at some point in future, but for now, it's a failure.

Nguyễn Thái Ngọc Duy (7):
  diff.c: keep all word diff structs together
  diff.c: refactor diff_words_append()
  diff --color-words: another special diff case
  diff.c: refactor fn_out_diff_words_write_helper()
  diff: unified diff with colored words, step 1, unified diff only
  diff.c: add new arguments to emit_line_0()
  diff --highlight-words: actually highlight words

 diff.c | 400 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 diff.h |   3 +-
 2 files changed, 363 insertions(+), 40 deletions(-)